Environmental rules: invisibility, hiding, darkness lacking

I am trying to find any rules specifically for darkness, hiding and invisibility and I am not finding anything in the rulebook for how these things are defined in this game and how they work mechanically. Even in the spells section, they are not defined. Can you even target a invisible, hidden or in darkness creature? The only thing we get is invisible attackers and blinded defenders modifiers. But it says nothing on how it works even though its expects these environmental features to come into play. Sure, I can house rule, but I am writing a published adventure here. I could use the SRD to define them but you'd think a game about dungeon crawling would have some rules on this stuff. So...how to proceed?